Molded explosive charge within a shell casing having an inner wall of absorbent material



United States Patent Olfice U.S. Cl. 102-24 Int. Cl. F42b 13/12 6 Claims ABSTRACT OF THE DISCLOSURE Novel explosive charges in a shell casing of improved thermal stability comprised of organic and/or inorganic nitro or nitrate compounds.

PRIOR ART One of the requirements of modern ammunition techniques is thermal stability of explosive charges and this requirement has been greatly intensified as compared to previous requirements. Modern conditions require a thermal stability at temperatures about 71 C. over extended periods of time as well as ability to sustain the aggravating conditions of tropical climates. Prior explosive charges, particularly charges based on highly nitrated aromatic compounds such as trinitrotoluene in combination with tetryl or nitropenta as a primer charge do not conform to these standards. In these explosive charges, secretions occur within the explosive charges at elevated temperatures which pass from the outer wall exposed to the heat first into the interior of the explosive thereby developing inhomogeneity in the explosive charge and a series of harmful reactions. The oily liquid secre tions consist essentially of low nitrated particles which are present in various percentages in nitro compounds, particularly trinitrotoluene, as impurities. Also, the tendency of trinitrotoluene to liquify is caused by eutectic mixtures with tetryl, nitropenta, etc.

The following disadvantages usually occur due to thermal instability of the explosive charges. The melting components travel from the inner wall to the hollow spaces which serve to accommodate the primer charges and they partly transform the primer charge composition into a viscous mass whereby the form of the primer charge is destroyed and a break in the ignition circuit occurs. The resulting liquid is also apt to penetrate the detonators and render these ineffective. In explosives, where the explosive charge is connected to mechanical devices, for

example to a timing apparatus, the liquid explosive can r OBJECTS OF THE INVENTION It is an object of the invention to provide novel explosives .with an improved thermal stability.

It is another object of the invention to overcome the disadvantages of known explosive charges in a simple, economical manner.

Patented Mar. 4, 1969 These and other objects and advantages of the invent1on will become obvious from the following detailed description.

THE INVENTION The novel explosive charges of the invention with improved thermal stability are comprised of a molded explosive charge within a shell casing whose inner wall is lined with a layer of a fibrous absorbent material, the explosive charge being comprised of a meltable without decomposing compound selected from the group consisting of organic nitro explosives and organic nitrated explosives and 0 to 50% by weight of inorganic nitrate explosives.

The layer of fibrous absorbent material not only acts as an insulating agent to prevent heat transmission but also acts as a means of absorbing any melted oily sub stances. It has been demonstrated that explosive charges, precast or press molded into said lined shell casings, retain their operatability, particularly their detonation sensitivity, even under the most exacting conditions to be encountered in tropical climates, i.e., at temperatures of C. for more than 120 hours.

Examples of particularly suitable absorbent materials are linters, cellulose, cotton, etc., although other absorbent materials may be used. The absorbent lining should be applied in a thickness adapted to the presently employed explosive charge and caliber and should be about 1.5 to 5 mm. thick. It may be introduced as a loose wall lining or in sheets extending from the top to the bottom. of the shell casing. It is also advantageous to line the primer charge with the absorbent material to prevent damage thereto by any liquid secretions.

The cast or press-molded explosive charges may be based on aromatic or aliphatic nitro compounds, such as trinitrotoluene, etc., alone or in admixture with other explosives, such as inorganic nitrates, trimethylenetrinitroamine, etc.

In the following examples there are described several preferred embodiments to illustrate the invention. However, it should be understood that the invention is not intended to be limited to the specific embodiments.

Example I A casting mixture consisting of of trinitrotoluene was poured into a mine shell of 70 mm. caliber iwhose interior was coated with a layer of linters about 1.5 mm. thick, and then, after the usual finishing process, a primer charge of tetryl was added. Then the explosive charge was stored for 72 hours at a temperature of 71 C. After this time, the exterior appearance of the explosive was found unchanged and it detonated perfectly at ignition.

Example II An explosive charge was prepared in the same manner as Example I, except that the coating layer of linters was omitted, and subjected to the same storage conditions.

After storage at the elevated temperatures, introduction of the detonator into the mine shell was no longer possible because the primer charge had become considerably deformed. To make the insertion of the detonator at all possible, the explosive charge had to be bored accurately to the size of gauge.

Example III In a corresponding manner, comparison tests to determine the storage stability at elevated temperatures were conducted with mine shells prepared as in Examples I and II at a temperature of 75 C. and for a period of storage lasting hours. The primer charge had been adjusted to press prior to the start of the storage at elevated temperature. After the tests had been completed,

the explosives were cut open. With regard to the shells with a linter lining, the primer charges, nitropent a and tetryl, were entirely unchanged, but in the shells without such a lining, the nitropenta or the tetryl was markedly fused with the trinitrotoluene of the main charge, and the primer charge was partly no longer identifiable as such. Consequently, the charges could not be used for practical purposes. As can be seen from the Example III, a substantial improvement of the previously known explosive charges is obtained with the present invention, and a further advantage, namely that the coating layer can be applied in a simple manner, is shown.

Various modifications of the compositions and method of the invention may be made without departing from the spirit or scope thereof and it is to be understood that the invention is to be limited only as defined in the appended claims.

We claim:

1. An explosive body with improved thermal stability comprising a molded explosive charge having a bore therein, a shell casing whose inner wall is lined with a layer of fibrous, absorbent material, a primer charge accommodated in a bore in said explosive charge, said explosive charge being enrobed in said layer whereby secretions from said explosive charge are absorbed, the explosive charge being comprised of a meltable without decomposing compound selected from the group consisting of References Cited UNITED STATES PATENTS 312,705 2/ 1885 Chamberlain 10259 316,970 5/1885 Hill 10259 896,887 8/1908 Bichel 149-105 987,590 3/1911 Murphy 10259 CARL D. QUARFORTH, Primary Examiner.

S. J. LECHERT, Assistant Examiner.

US. Cl. X.R. 149-44, 15; 10256 

